Higher rank multiple input multiple output enhancements in millimeter wave and sub-Terahertz bands

Abstract

Methods, systems, and devices for wireless communications are described for implementation of higher rank transmissions (e.g., higher rank line of sight (LOS) schemes) over a given beam direction associated with a selected transmission configuration indicator (TCI) state. According to some aspects, expanded antenna arrays, spatial separation (e.g., distance) between antenna elements, lower carrier frequencies (e.g., associated with frequency range 4 (FR4) systems), etc. may be leveraged to communicate uncorrelated signals (e.g., independent streams across spatial layers) for higher rank transmissions using a given TCI state (e.g., using a single beam direction). Various aspects of the described techniques may provide for higher rank directional communications by a user equipment (UE) (e.g., via uncorrelation in a single UE), higher rank directional communications by select UEs (e.g., via uncorrelation across specific UEs), base station antenna selection for uncorrelation at multiple served UEs, etc.

What is claimed is: 
     
       1. A method for wireless communication at a first wireless device, comprising:
 determining a spatial separation distance between at least two transmitting entities or at least two receiving entities; 
 determining a rank associated with a beam direction based at least in part on the spatial separation distance for the at least two transmitting entities or the at least two receiving entities; and 
 transmitting at least two uncorrelated signals over the beam direction based at least in part on the rank associated with the beam direction. 
 
     
     
       2. The method of  claim 1 , further comprising:
 transmitting an indication of the beam direction and the rank associated with the beam direction. 
 
     
     
       3. The method of  claim 2 , further comprising:
 transmitting or receiving at least two uncorrelated signals over the beam direction based at least in part on the transmitted indication. 
 
     
     
       4. The method of  claim 1 , wherein determining the spatial separation distance between the at least two transmitting entities or the at least two receiving entities comprises:
 determining a spatial separation between at least two antenna modules of the first wireless device. 
 
     
     
       5. The method of  claim 4 , further comprising:
 transmitting an indication of an availability of the at least two antenna modules to transmit the at least two uncorrelated signals over the beam direction, receiving at least two uncorrelated signals over the beam direction, or both. 
 
     
     
       6. The method of  claim 4 , further comprising:
 determining an orientation of each of the at least two antenna modules, wherein the rank associated with the beam direction is determined based at least in part on the orientation of each of the at least two antenna modules. 
 
     
     
       7. The method of  claim 6 , wherein determining the rank associated with the beam direction comprises:
 determining a number of independent layers that can be processed with analog precoding for transmitting or receiving uncorrelated signals over the beam direction based at least in part on the spatial separation between the at least two antenna modules, the orientation of each of the at least two antenna modules, or both. 
 
     
     
       8. The method of  claim 1 , wherein determining the spatial separation distance between the at least two transmitting entities or the at least two receiving entities comprises:
 determining a spatial separation between the first wireless device and a second wireless device. 
 
     
     
       9. The method of  claim 8 , further comprising:
 transmitting, to a third wireless device, an indication of the beam direction and the rank associated with the beam direction, wherein the rank comprises a capability of the first wireless device and the second wireless device to transmit or receive uncorrelated signals to or from the third wireless device over the beam direction. 
 
     
     
       10. The method of  claim 8 , further comprising:
 receiving positioning information from the second wireless device via a device-to-device wireless link, wherein the spatial separation between the first wireless device and the second wireless device is determined based at least in part on the received positioning information. 
 
     
     
       11. The method of  claim 10 , further comprising:
 transmitting, to the second wireless device, signaling to coordinate antenna module usage of the first wireless device and the second wireless device. 
 
     
     
       12. The method of  claim 8 , further comprising:
 transmitting positioning information of the first wireless device to a third wireless device; and 
 receiving positioning information of the second wireless device from the third wireless device, wherein the spatial separation between the first wireless device and the second wireless device is determined based at least in part on the received positioning information of the second wireless device. 
 
     
     
       13. The method of  claim 1 , wherein determining the spatial separation distance between the at least two transmitting entities or the at least two receiving entities comprises:
 determining a spatial separation between a first antenna element of the first wireless device and a second antenna element of the first wireless device. 
 
     
     
       14. The method of  claim 1 , further comprising:
 receiving an indication of the rank associated with the beam direction. 
 
     
     
       15. The method of  claim 14 , wherein determining the rank associated with the beam direction comprises:
 determining the rank, of a second wireless device, associated with the beam direction, wherein the at least two uncorrelated signals are transmitted or received over the beam direction to or from the second wireless device based at least in part on the determined rank, of the second wireless device, associated with the beam direction. 
 
     
     
       16. The method of  claim 1 , further comprising:
 receiving an indication of an availability of two antenna modules of a second wireless device to transmit the at least two uncorrelated signals over the beam direction, receiving the at least two uncorrelated signals over the beam direction, or both, wherein the at least two uncorrelated signals are transmitted to or received from the second wireless device over the beam direction based at least in part on the received indication. 
 
     
     
       17. The method of  claim 1 , further comprising:
 receiving an indication of the beam direction and the rank associated with the beam direction, wherein the rank comprises a capability of a second wireless device and a third wireless device to receive uncorrelated signals from the first wireless device over the beam direction. 
 
     
     
       18. The method of  claim 17 , wherein transmitting the at least two uncorrelated signals over the beam direction comprises:
 transmitting a first signal to the second wireless device over the beam direction; and 
 transmitting a second signal to the third wireless device over the beam direction, wherein the first signal and the second signal are uncorrelated at the second wireless device and the third wireless device. 
 
     
     
       19. The method of  claim 18 , further comprising:
 transmitting an indication that the first signal corresponds to the second wireless device and that the second signal corresponds to the third wireless device. 
 
     
     
       20. The method of  claim 1 , further comprising:
 selecting a first subset of antennas from an antenna array of the first wireless device based at least in part on the rank associated with the beam direction; and 
 selecting a second subset of antennas from the antenna array of the first wireless device based at least in part on the rank associated with the beam direction, wherein the at least two uncorrelated signals are transmitted over the beam direction based at least in part on the selected first subset of antennas and the selected second subset of antennas. 
 
     
     
       21. The method of  claim 20 , wherein transmitting the at least two uncorrelated signals over the beam direction comprises:
 transmitting a first signal to a second wireless device based at least in part on the selected first subset of antennas; and 
 transmitting a second signal to a third wireless device based at least in part on the selected second subset of antennas. 
 
     
     
       22. The method of  claim 21 , wherein the first subset of antennas are selected based at least in part on spatial separation distances between antenna elements of the first subset of antennas and a first distance between the first wireless device and the second wireless device, and wherein the second subset of antennas are selected based at least in part on spatial separation distances between antenna elements of the second subset of antennas and a second distance between the first wireless device and the third wireless device. 
     
     
       23. The method of  claim 1 , further comprising:
 determining a distance between the first wireless device and a second wireless device; and 
 determining a number of receive antenna elements associated with the second wireless device, wherein the rank associated with the beam direction is determined based at least in part on the distance between the first wireless device and the second wireless device, the number of receive antenna elements associated with the second wireless device, or both. 
 
     
     
       24. The method of  claim 1 , further comprising:
 determining a carrier frequency associated with communications between the first wireless device and a second wireless device, wherein the rank associated with the beam direction is determined based at least in part on the determined carrier frequency. 
 
     
     
       25. The method of  claim 1 , wherein the beam direction is associated with a line of sight path or a non-line of sight path along a dominant cluster. 
     
     
       26. A method for wireless communication at a first wireless device, comprising:
 receiving an indication of a beam direction and a rank associated with the beam direction; and 
 receiving at least two uncorrelated signals over the beam direction based at least in part on the rank associated with the beam direction. 
 
     
     
       27. The method of  claim 26 , further comprising:
 receiving a first positioning signal from a second wireless device; 
 receiving a second positioning signal from a third wireless device; 
 determining a distance between the second wireless device and the third wireless device based at least in part on the received first positioning signal and the received second positioning signal; and 
 transmitting an indication of the distance to the second wireless device and the third wireless device, wherein the indication of the beam direction and the rank associated with the beam direction is received based at least in part on the transmitted indication of the distance. 
 
     
     
       28. The method of  claim 26 , further comprising:
 receiving an indication of antenna module availability of a second wireless device to transmit the at least two uncorrelated signals over the beam direction, wherein the at least two uncorrelated signals are received based at least in part on the received indication of the antenna module availability of the second wireless device. 
 
     
     
       29. A method for wireless communication at a first wireless device, comprising:
 transmitting an indication of a beam direction and a rank associated with the beam direction; and 
 receiving at least one signal over the beam direction based at least in part on the rank associated with the beam direction. 
 
     
     
       30. The method of  claim 29 , further comprising:
 determining a distance between the first wireless device and a second wireless device, wherein the indication is transmitted based at least in part on the distance.